Control gates

1. A control gate adapted to be installed across a channel for liquids, the control gate comprising a barrier member with at least one side member, the barrier member being pivotally mounted at or adjacent the base of the channel, a drive member co-operating with the at least one side member to allow raising and lowering of the barrier member to regulate flow of liquid through the control gate, and a flow stabilization device including a flow direction plate pivotally attached to the barrier member and adapted to retain a substantially parallel disposition with respect to the floor of the channel so as to allow flow of liquid through the control gate substantially parallel to the floor of the channel, wherein, being retained in the substantially parallel disposition, the flow direction plate forms one side of a parallelogram the opposite side of which being formed by an arm fixed in a position substantially parallel to the floor of the channel.

2. The control gate of claim 1 , wherein the at least one side member has a circular arcuate section which co-operates with the drive member.

3. The control gate of claim 2 , wherein the drive member includes a rack or chain on the circular arcuate section which co-operates with a driven pinion, worm or sprocket.

4. The control gate of claim 2 , wherein the drive member includes a winding spool which co-operates with at least one cable along or parallel to the circular arcuate section whereby the winding onto or off the winding spool of the at least one cable will cause movement of the barrier member.

5. The control gate of claim 4 , wherein the winding spool is movable axially during rotation to allow cables to wind around the winding spool at a substantially constant axial position thereon.

6. The control gate of claim 2 , wherein the circular arcuate section includes a flange which projects into the flow of liquid to alter the characteristics of liquid flow through the control gate.

7. The control gate of claim 1 , further comprising a support frame to which the at least one side member is sealingly engaged within the channel.

8. The control gate of claim 1 , further including a first pressure sensor for measuring the pressure of the liquid at a first position upstream of the barrier member, a second pressure sensor for measuring the pressure of the liquid at a second position downstream of the barrier member, an opening sensor for measuring the position of opening of the barrier member and computation means for calculating the rate of the flow based on the measurements.

9. The control gate of claim 8 , wherein the flow rate calculation uses a system identification method.

10. The control gate of claim 1 , further including first and second sensors located, respectively, upstream and down stream of the barrier member for measuring velocity of the liquid in the channel, each of the first and second sensors being one or more of pressure, electromagnetic, or sonar sensors, a third sensor for measuring opening positions of the barrier member and computation means for processing the measurements.

11. The control gate of claim 1 , further comprising a first frame member adapted to be secured to the channel and a second frame member slidingly received by the first frame member, the barrier member being pivotally attached to or slidingly inserted into the second frame member, a first sealing member between the barrier member and the second frame member, and a second sealing member between the first and second frame members.

12. The control gate of claim 11 , wherein the first and second sealing members are each a continuous seal abutting or attached to the second frame member.

13. The control gate of claim 12 , wherein the continuous seal includes a plurality of parallel ribs to provide a positive sealing effect.